Anode assembly for cathodic protection system



Sept. 9, 1958 H. w. HOSFORD, JR 5 ANODE ASSEMBLY FOR CATHODIC PROTECTION SYSTEM Filed July 2, 1957 INVEIQTOR. HARRY MHOWORDJR. 1 BY A TTOPNEYS- United States Patent O" ANODE ASSEMBLY FOR CATHODIC PROTECTION SYSTEM This invention relates as indicated to a novel anode as sembly for cathodic protection systems, and more particularly to improved anodes or electrodes adapted to be interconnected for suspension within water tanks and the like to protect the latter against corrosion.

Elongated anodes which may be of aluminum or graphite, for example, are commonly suspended in large steel water tanks to prevent corrosion of the latter, a proper voltage being maintained to prevent solution of the iron. The anodes, of course, gradually disintegrate. They are generally in the form of long rods or bars suspended from the roof of the tank and may be quite heavy. Reference may be had to my prior Patent 2,704,649 for further description and illustration of the manner of employing such electrodes.

The importance of providing cathodic protection to water tanks and many other similar installations has now become generally recognized and cathodic protection systems are utilized on a very large scale. A principal source of expense both in initial installation and subsequent maintenance are the electrodes themselves which must be of appropriate length and suitability for conducting an electric current. As such electrodes gradually corrode in use, they must be periodically inspected and eventually withdrawn and replaced. There has accordingly been a search for suitable anode materials having a reasonably low initial cost and long life expectancy. In some respects, Duriron, a 14% silica cast iron, is especially suitable, being highly corrosion resistant and not exceptionally expensive. It suffers from the defect, however, of being fragile and brittle, requiring careful handling of the elongated electrodes to avoid breakage. When using such Duriron electrodes, it has been standard practice to make them of rather large diameter with recesses in their respective ends to receive a brass drive bushing to which an appropriate conductor. such as an insulated copper lead wire may be brazed. It is very difficult to weld Duriron and similar high silica cast iron. It is also extremely diificult to braze a copper wire to the end of a Duriron electrode inasmuch as it is necessary to heat ,such electrode to a very high temperature and embrittleent of the wire occurs. Inasmuch as the electrodes are suspended by means of the current carrying conductor wires, it is obvious that the latter must be non-brittle and sufiiciently strong to support such electrodes with an adequate safety factor. 1

V In order to attach the lead wires to the electrodes by known means in the past, such as such drive bushing, it has been necessary to employ electrodes of very substantial thickness, the electrodes being of considerably greater diameter than would otherwise be required in view of their high degree of corrosion resistance. This not only adds directly to the cost of the system, but also requires the employment of heavier and stronger lead wires interconnecting a series of such electrodes for suspension from the tank roof, and this in turn increases shipping and handling costs.

"2,851,413 Patented Sept. 9, 1958 In view of the foregoing,

provide a method of securing a current conducting lead wire to the end of a small diameter high silica cast iron electrode.

Still another object is to provide an electrode assembly which will be highly effective in use but relatively inexpensive, of low aggregate weight and adapted to be assembled or repaired in the field.

Other objects of the invention scription proceeds.

To the accomplishment of the foregoing and related ends, said invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

In said annexed drawing:

Fig. l is a semi-diagrammatic vertical section taken through a typical water tank and stand pipe showing strings of elongated electrodes suspended therein as part of a cathodic protection system;

Fig. 2 is a detail view of a small diameter high silica cast iron electrode;

Fig. 3 illustrates a step in the provision of lead wire attaching means for such electrode;

Fig. 4 shows a subsequent step in the modification of such electrode;

Fig. 5 is a fragmentary detail view illustrating the attaching of a lead wire to an end of such prepared elec trode; and

Fig. 6 shows the final wrapped connection which reinforces and protects the joint.

Referring now more particularly to such drawing and especially Fig. 1 thereof, it is now common practice to suspend strings of elongated electrodes 1 from the roof 2 of a water tank 3, such electrodes hanging freely out of electrical contact with the tank and connected in' known manner in an electric circuit therewith as explained more in detail in my aforesaid Patent 2,704,649. The electrodes are interconnected by flexible wires such as 4 which are ordinarily of copper and must be insulated from the contents of the tank to avoid rapid corrosion and destruction. A central string of anodes 5 may be suspended from the roof of the tank to hang within the elongated stand pipe 6.

In 'the preferred embodiment of my invention illustrated, I make use of commercially available Duriron weld rod which is about inch in diameter and is available in lengths of about 14 inches. Such weld rod is very fragile and easily broken if dropped but its corrosion rate is negligible for. practical purposes when utilized as an anode in an ordinary cathodic protection system. I find it very advantageous to employ such small diameter electrodes .since they are considerably cheaper than the high silica cast iron electrodes previously utilized and they are much easier to handle and install. With such small diameter rod, however, it is not feasible to drill holes in the ends to receive drive bushings and the like. Certain other types of attaching means proved impractical in view of the fragility of the material, and direct brazing of the lead Wire to the end of the electrode likewise proved unsatisfactory due to embrittlement of the wire which must, of course, suspend the electrodes in use as well as conduct the relatively small current involved.

will appear as the de- After testing a variety of methods, all of which proved unsatisfactory, I developed the technique illustrated in Figs. 2-6 inclusive of the drawing. As shown in Fig. 2, the ends 7 and 8 ofv the high silica cast iron electrode are first ground off flat transversely of the rodand I then heat the end of the rod with an acetylene torch or equivalent means until the end of the rod has been raised to a cherry red temperature extending approximately /2 inch back along the rod. A brass brazing'rodwith conventional flux is then applied to melt a small puddle or button such as 9 of brass on the ground end of the rod and a short tubular copper sleeve 10 is pushed into such puddle co-axially of rod 1. 7 Such sleeve 10 is of smaller diameter than rod'l and may be of a material ,other'than copper such as brass or steel. The molten brass 9 and the flux wet the sleeve and bond the latter in position as shown in Figs. 4 and 5. A similar sleeve is, of course, likewise secured to the other end of the electrode 1.

Referring now especially to Figs. and 6 of the drawing, I insert the end of a stranded copper conductor or lead wire 11 within sleeve and crimp the latter firmly as at 12 to grip conductor 11 to form a strong mechanical and good electrical connection. It will be appreciated, of course, that the electric current required to be conducted through such connection is very small. As pointed out above, the flexible lead wire 11 is enclosed with suitable waterproof insulation 13 and I now wrap the joint with waterproof adhesive insulating tape 14 as shown in Fig. 6 fully to enclose the braze 9, the crimped sleeve 10 and the exposed conductor 11. This wrapping both protects such portions from corrosion and also serves to strengthen the joint and prevent undesired sharp flexing of the conductor in such region. I have found, however, that with my new mode of attachment, considerable flexing may be withstood without any damage to the assembly inasmuch as the conductor is mechanically attached to the electrode without being heated or in any way damaged.

Because the electrodes may now be of relatively light weight, an entire string may be interconnected and inserted within a water tank by a single man and handling problems and breakage are much reduced. Moreover, should an electrode in the chain become broken prior to installation, it is an easy matter to substitute a new electrode in the field, something previously impractical. Due to the light weight of the electrodes, I am enabled to utilize No. 14 wire for interconnecting and suspending the same whereas previously No. 8 wire had been found necessary. My new technique may be employed with other electrodes such as stainless steel electrodes, for example, but is particularly advantageous when using the hard fragile high silica cast iron electrodes such as Duriron weld rod. The usual formula for Duriron is: silicon 14.5%, carbon 0.85%, manganese 0.65%, molybdenum 0%, iron-the remainder, all by weight. I prefer to employ a commercially available borax flux in the brazing operation. .While the rod will ordinarily be inch-diameter, other .small sizes such as inch may also be utilized. v

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims or the equivalent of such be employed.

I therefore particularly point out and distinctly claim as my invention:

1. An anode assembly for use in a cathodic protection system comprising a plurality of high silica iron elongated electrodes interconnected by flexible insulated conductors, said electrodes having short tubular sleeves brazed to the respective ends thereof substantially co-axial therewith, said sleeves being crimped to make electrical contact with and mechanically grip the respective inserted ends of said flexible conductors whereby said electrodes are thus connected together in series, and waterproof insulation enclosing said braze sleeve and conductor extending from the insulation on said conductors to the respective electrodes, the surfaces of which latter are substantially entirely exposed.

2. The assembly of claim 1, wherein said electrodes are of high silica iron having a silica content of approximately 14%.

3. The assembly of claim 1, wherein said electrodes are of high silica iron having a silica content of approximately 14%, said electrodes each being approximately 14 inches long and inch in diameter.

4. The assembly of claim 1, wherein said electrodes are of high silica iron having a silica content of approximately 14%, said electrodes each being approximately 14 inches long and inch in diameter, and said flexible conductor is stranded copper wire on the order of No. 14

5. In a cathodic protection system for water tanks and the like comprising a series of elongated high silica iron electrodes suspended within such tank and means for imposing a voltage differential between said electrodes and such tank, with said electrodes serving as anodes in the system; flexible electrical conductive means interconnecting said electrodes comprising lengths of flexible wire extending between successive electrodes, tubular sleeves brazed to the ends of said electrodes, the respective ends of said lengths of wire being inserted therein and said sleeves crimped mechanically to grip said wires and to make electrical contact therewith, and insulation enclosing said wires, said sleeves and braze to expose only the surfaces of said electrodes to the contents of such tank.

6. The assembly of claim 5, wherein said electrodes are of Duriron and said sleeves and wires are of copper.

7. The assembly of claim 5, wherein the insulation enclosing said crimped sleeves and immediately adjoining portions of said conductors and electrodes is relatively bulky and rigid in contrast to the insulation enclosing said flexible wires so that the connections are protected against excessive flexing and the fragile electrodes are cushioned against impact with adjoining surfaces.

References Cited in the file of this patent UNITED STATES PATENTS 1,489,743 Delius et al. Apr. 8, 1924 1,788,485 Gunderson Ian. 13, 1931 2,467,852 Pinner Apr. 19, 1949,; 2,723,230 Godsey Nov. 8, 1955' 2,782,491 Cole Feb. 26, 1957 2,782,492 Frost Feb. 26, 1957 2,803,602 De Cowsky et al Aug. 20, 1957 2,808,373 Andrus Oct. 1, 1957 

1. AN ANODE ASSEMBLY FOR USE IN A CATHODIC PROTECTION SYSTEM COMPRISING A PLURALITY OF HIGH SILICA IRON ELONGATED ELECTRODES INTERCONNECTED BY FLEXIBLE INSULATED CONDUCTORS, SAID ELECTRODES HAVING A SHORT TUBULAR SLEEVES BRAZED TO THE RESPECTIVE ENDS THEREOF SUBSTANTIALLY CO-AXIAL THEREWITH, SAID SLEEVES BEING CRIMPED TO MAKE ELECTRICAL CONTACT WITH AND MECHANICALLY GRIP THE RESPECTIVE INSERTED ENDS OF SAID FLEXIBLE CONDUCTORS WHEREBY SAID ELECTRODES ARE THUS CONNECTED TOGETHER IN SERIES, AND WATERPROOF INSULATION ENCLOSING SAID BRAZE SLEEVE AND CONDUCTORS EXTENDING FROM THE INSULATION ON SAID CONDUCTORS TO THE RESPECTIVE ELECTRODES, THE SURFACES OF WHICH LATTER ARE SUBSTANTIALLY ENTIRELY EXPOSED. 